| 摘要 |
PROBLEM TO BE SOLVED: To simplify braking control at a very slow speed and provide natural operation feeling in an electric car with a mechanical braking mechanism and electric braking mechanism. SOLUTION: When required braking force is smaller than a specified value, braking force (initial friction braking force) is generated only by a friction brake mechanism, i.e., a mechanical braking mechanism. That is, a proportioning valve is provided. This proportioning valve has such properties that when the pressure of a master cylinder(M/C) is smaller than a specified value P1 , M/C pressure and the pressure of a wheel cylinder(W/C) are made same as each other, and when it exceeds the specified value, W/C pressure is not increased or slightly increased compared with an increase in M/C pressure. The specified value P1 of this M/C pressure is determined based on the upper limit of the range of the braking force used when the vehicle runs at a very slow speed. Therefore, while the vehicle runs at a very slow speed, braking force is controlled not by an electric braking mechanism, but by the mechanical mechanism, providing simple control. |
